The present invention relates to a nasal cannula assembly for use in the administration of fluids such as oxygen into the nasal passages of a person having respiratory ailments.
In the past, flexible cannulas have been produced that were positioned to contact the nasalabidial area between the patient's upper lip and nostrils (see U.S. Pat. Nos. 2,868,199 and 3,802,431). Even though these cannulas were made of soft, flexible plastic, the wearer encountered discomfort.
When a patient is required to have prolonged oxygen administration, it is necessary that the cannula be worn both during awakening hours as well as sleeping hours. This results in continued contact of the cannula especially at the philtrum and around the unprotected upper lip area causing irritation and inflamation. While the patient is talking or eating, rubbing contact occurs and even while sleeping, rubbing occurs as the patient inadvertently moves his head from side to side. As is the case in any instance of prolonged contact of a patient's skin with a foreign object, not only does irritation result, but inflamation and ulcerous conditions may occur after a period of time.
The contact problem in the nasalabidial area has also been compounded by the manner in which the cannula is held in position on the patient. Generally, the nasal extensions were inserted into the nostrils and an upward and rearward tension was applied to the cannula by the auxiliary oxygen supply tubes connected to the opposite ends of the cannula. These auxiliary supply tubes were pulled over the patient's ears and then looped downward and were cinched up relatively snugly by a slip loop passing around the two auxiliary supply tubes. In the absence of looping the supply tubes over the patient's ears, the weight of the cannula itself would cause the cannula to disengage itself from the nostrils and fall from the patient when his head was in an upright position. The pull of the auxiliary supply tubes caused pressure stresses where the cannula was pulled against the nasalabidial area.
Another prior cannula structure, (see U.S. Pat. No. 3,643,660), has been designed to eliminate contact in the nasalabidial area. Its shortcomings result from the fact that the lower edge of its flat upper surface bears against the upper nasalabidial area of the patient thereby creating an area susceptible to irritation and inflamation. This lower edge provides a relatively lengthy edge along which pressure is applied. Also, the auxiliary oxygen supply tubes extend outwardly from the cannula along the longitudinal axis of the cannula thereby requiring a pronounced tension on the supply tubes from around the top of the patient's ears again accentuating the pressure being applied against the patient's uppermost nasalabidial zone. The flat nature of the top surface of the cannula also increases the area of contact of the cannula with the anterior nares.